With the development of times, cooking appliances are increasingly diverse. At present, a novel barbecue type cooking appliance appears in the market, as shown in FIG. 1 and FIG. 2, the cooking appliance includes an oven door 2′ and a base 1′, the oven door 2′ is articulated to the base 1′ and can rotate up and down, an upper heating tube 3′ is installed on the inner side the oven door 2′, and a housing of the base 1′ includes a front control panel 11′ in the front, a bottom plate 12′ at the bottom, outer covers 13′ on left and right, a rear plate 14′ on the back and a top plate at the top. The top plate is a cavity 15′ having an opening upward, a lower heating tube 4′ is installed inside the cavity 15′, two waveguide tubes are welded to the bottom of the cavity 15′, a magnetron 5′ is arranged at the edge of each of the two waveguide tubes, and a high voltage transformer 6′ is installed nearby the magnetrons 5′. In order to dissipate the heat of the magnetrons 5′ and the high voltage transformer 6′, the product needs three fans 7′, the first fan 7′ sucks air from air inlets of the left and right outer covers 13′ and blows air to the right magnetron 5′ to dissipate the heat of the right magnetron 5′, and the air flowing through the right magnetron 5′ is guided to the rear plate 14′ via an exhaust air duct 9′ and an exhaust tube 8′ and discharged out of the product via an exhaust hole of the rear plate 14′. The second and third fans 7′ are separately installed on the left and right of the high voltage transformer 6′, wherein the second fan 7′ sucks air from the air inlet of the adjacent outer cover 13′ and blows air to the high voltage transformer 6′ to dissipate the heat of the high voltage transformer 6′, then the third fan 7′ sucks the air flowing through the high voltage transformer 6′ and blows air to the left magnetron 5′ to dissipate the heat of the left magnetron 5′, and finally, the air flowing through the left magnetron 5′ is guided to the rear plate 14′ via the exhaust air duct 9′ and the exhaust tube 8′ and discharged out of the product via the exhaust hole of the rear plate 14′. The heat dissipation air duct system needs three fans, so that many parts are needed, the cost is high, the assembly time of the product is long and the production efficiency is low.